Upgrading the 3 speed automatic transmission

So not sure if you are suggesting that the shift kit or the 10" torque converter caused the harder shifts (bang) on the differential. I also noticed that the TCI gearset is for the 350.

 

The link for your 10" TCI Torque Converter appears to have a 24--2600 stall speed. Is that correct. My torque converter is around 1600-1800 which seemed to feel right.

 

TCI has a low gear set specifically for the TH400. Will get you the part #.

Sent from my MAR-LX1M using Tapatalk

 

I’ve done a couple of shift kits although haven’t done on on a TH400. There are usually options as to how firm you want the shifts. I’ve found usually the smallest amount to be a good choice. Of course talking to a shop specializing in these transmissions is always the best way to go.

 

As the converter is the first in the chain to receive the bulk of the torque coming from the V12, a high stall converter somehow soften the stress on the gear-train. That's at least my experience with the variable stall converter: the "bangs" were much louder when running on low stall (~1200rpm) versus high stall (~2400rpm).

So with my aggressive shift kit, a high stall setup is more appropriate. Sticking to the regular shift kit would probably make our life easier, but with a lousy (i.e high stall) converter the gearbox becomes even more "mushy". Not what I want from a proper Ferrari.

The point is to find a proper balance of higher stall and firmer shift.

 

Regarding the shift "kit", I also have to say that my gearbox does not have such a kit... My tranny was commissioned to Jakes Performance who do not use off-the-shelf kits. Just quoting them "The TransGo kit is an excellent product and it works, but the knowledgeable builder can build the transmission without using any kit and save money." They just shipped my transmission with a no-nonsense setup and facilitated us a set of instructions on how to dial it on our own. To be clear they even posted to my mechanic the full lists of modifications made to the transmission so that we could rebuild it on our own if need be.

If like me, you are an overseas customer, you may not have a nearby (performance) transmission specialist that can perform all the fine-tuning. In this case, being in a position to locally dial the transmission on your own is really a must. My money goes to the well documented products, rather than off the shelf "kit".




PS : all settings tweaked to the max now

 

Look forward to receiving the part number for the 400 gears. The tranny hasn't been pulled yet, so still waiting to see if the bearing is the main culprit. Also will find out which manufacturers high stall speed Torque Converter was installed.

 

Thank you for all input, much appreciated.

My TH400 is coming out the week after next and going to a GM gearbox "guru" in our neck och the woods. He will undoubtedly know what to do.

If he happen to have a set of "low gear" on the shelf maybe we do that also. If not, I will stick to stock gears.

Not sure he will mount the full TransGo shift kit, I will follow his recommendations. I have had the kit for a long time and really bought it due to the TH400 OEM accumulators pistons sometimes being plastic (and crack from aging) and in my TransGo shift kit they are aluminum.

My car has only covered 35k km's so I hope most parts are in good shape but the additional cost to swap in new seals and bearings is small compared to in & out costs so we will do a full rebuild. After all it is 42 years old by now. Not sure the filter has been changed ever....

I will revert with the results here in a few weeks.

He typically mount custom billet converters on the race cars but he confirmed that the selected TCI converter should work. It is by no means a race converter but should be a few notches up from stock. Unless having more horsepower than we do and/or going racing he said that choice of converter brand is really personal preference. If using a brand name reinforced converter with similar characteristics they should all work good in this application.

He thought a reinforced 10" converter should be fine as long as the pump is fine. They put significant higher horse power through the ones they install. I guess it is also relative to how heavy your right foot is.

I choose TCI mainly as it has dual mounting patterns (later found out that so do other brands) and I hope that at least one of them fits the stock Ferrari flexplate without drilling. If it does not, I could have chosen any quality converter brand (ATI, Hughes, JW, FTI or other). My shop seem to prefer Hughes for standard converters. They also have a full test bench where the can run the gearbox outside the car with load.

When talking to the shop (and others) they said there are so many different variables to figure out the actual stall speed on a particular car. The specified stall range from TCI is a "guesstimate" on a mildly upgraded GM small block engine (approx. 2200-2400 rpm stall). Our engines are different and with the torque curve max being at higher RPM (4300-ish rpm)
than a GM SB (sub 4000rpm) may provide a slightly lower stall speed in the same weight car. In best case maybe around the above recommended 2000 rpm.

Well, in a few weeks we will know

//Rob

 

Attached. Image Unavailable, Please Login

Sent from my MAR-LX1M using Tapatalk

 

Thanks for the follow up. Will send this to my tranny rebuilder. This and the high stall should really help optimize the torque curve on the 400

 

Competizione took the Th400 out and the input spline shaft had some wear. Won't know if there is any other issues until it is torn down. I will be taking the TH400 to Performance Automatic's HQ i(PA)n MD. I will suggest the 2.75 gearset along with the raybestos and transco shift kit. Not sure if we will keep the existing hi stall torque converter. Richard at Competizione said the diff on the 400 is strong enough to handle the tighter shifting from the shift kit. I will be meeting with the head guy at PA who has modified TH400's for every type of situation. He will look at all the factors from the diff/ gear ratio/ torque converter and torque curve to optimize the setup. While they may recommend a rebuilt tranny off the shelf, I want to keep the original casing. I noticed the casing has an ID tag that states 78 FER (my model year). Shift kits can also be adjusted to the degree of "tightness" of the shifts as well as the modulator. So hopefully the end result will be better fit. Fortunately, Richard at Competizione has an 81 400i and is very familiar with the car.

 

Sounds like we are on similar time lines. I left my 1980 at the shop last Friday, they will take out the gearbox today or tomorrow and sent it to a specialist for a rebuild. The specialist will have to determine how far we go with the shift kit. I do want a firm shift but no "gun-shot" shifts.

I will skip the lower gears for now as I can't get them within the time window available. It appears that TCI no longer makes them. I will also swap in an electronic speedo sensor as I have a brand new electronic speedo on the shelf and the mechanical has always showed too high numbers. Dakota digital makes a Bluetooth enabled adapter to set the speed readout using a GSPS for reference.

We will also put some color on the additional sub frame that was installed when she was turned into a convertible. -And swap in some new braided brake lines as well, as they are difficult to reach with the sub frame in place.

We should get her back at the end of next week according to plan and I will report back the findings. I'm very interested in how the new converter will affect the driving. The stock converter shifts at very low RPM's and I hope to cure some of that. Reduced size may also affect response i hope.

 

I dropped off the tranny and Torque Converter at Performance Automatic. They noted that ordering the gears may take a week or two. The 12" Torque converter will be cut open so they inspect and adjust the stators to a 1600-1800 stall or possibly higher. They will adjust the valve bodies to make for tighter shifts, but not heavy bang shifts. The last thing I want is to smoke the tires on a 1st to 2nd shift.

 

Smoking the tires on a 400 Auto would require starting on a wet road or sand.

 

Performance Automatic spoke to TCI about the 2.75 gearset. TCI indicated that they have stopped production of the gearset due to quality issues. I believe he mentioned that another company has a 2.75 gearset, but these are straight cut gears for drag racing and not suitable for the TH 400. They will now "tweak" the Torque Converter to improve the low end.

 

Well, bit the bullet and shipped a transmission to Kilgore for the 2.75/1.57/1 ratio and all other updates he recommends . Am leaning towards the TCI Saturday Night Special or a B&M Holeshot 2000. Will let you know how it goes. Will probably be a bit before I get it back and installed.

 

Great, we will be two then with the low gear set.

I will do some before/after 0-60 runs to compare.

You should notice a dramatic improvement. Kilgore will also do some other improvements, great guy.

Sent from my MAR-LX1M using Tapatalk

 

Who will be providing the 2.75 gearset as TCI no longer sells them?

 

John kilgore makes lots of heavily customed parts for these transmissions. My guess is that these are "his" (or specifically made for him).

 

I went to the Kilgore site, but couldn't tell if the 2.75 set uses straight cut gears. Straight cut gears may provide the strength needed for drag racing but are not well suited for a moderate street vehicle like the 400. My guy at Performance Automatic said that the 2.75 gearsets he found from different manufacturers were for drag racing and thus straight cut. So I am interested to know if someone has found 2.75 gears that are not straight cut For me it may be too late since I picked up the transmission today and have a new 2400 Torque converter from Hughes. I will be bringing the tranny and TC to Competizione and Sport tomorrow for installation.

 

See my post - I have the TCI unit and it is NOT straight cut. Kilgore knows what is he doing, and putting straight cut gears on a road cars would be nonsense.

 

Very curious to hear about your test drive. I didn't know Richard had a 400 too, I've spoken to him many times over the years but we never discussed what cars we own.

 

So Kilgore procured the gears from TCI? Very curious since Performance Automatic spoke to TCI and said they were no longer producing the gear set.

 

Kilgore is not doing my transmission, I purchased my gear from a private seller.

 

Hello,

I have been offered another low gear set, 3.07/1.57 from Kilgore.

Is virtually new, PM me if anyone is interested.



Sent from my MAR-LX1M using Tapatalk